A GOA (Gate Driver On Array) circuit uses an array process of conventional liquid crystal display process to formed a gate scan drive circuit on a substrate, in order to achieve the progressive scan drive. It has the advantage of reducing production costs and narrow border design for a variety of displays used. GOA circuit has to have two basic functions: the first one is to input a gate drive pulse and drive a gate line in the panel to open a TFT (Thin Film Transistor, thin-film transistor) in display area, charging pixels by the gate line; the second one is to provide a shift register circuit to, when the n level gate driver pulse output is completed, output the n+1 gate drive pulse by a clock control, and so passed on.
GOA circuit includes a pull-up circuit, a pull-up control circuit, a pull-down circuit, a Pull-down control circuit and a boost circuit for rising the electric potential. Specifically, the pull circuit is mainly responsible for outputting the input clock signal (Clock) to gate of the thin film transistor as a drive signal of liquid crystal display. The pull-up control circuit is responsible for controlling open of the pull-up circuit, usually effected by a signal transmitted from the previous level GOA circuit. The pull-down circuit is responsible for after output a scan signal, pulling down the scan signal to low potential rapidly, i.e. pulling down electric potential of gate of the thin film transistor to low potential; the pull-down control circuit is responsible for keeping the scan signal and signal of the pull-up circuit (commonly referred to the Q point) in a closed state (i.e. set negative potential), usually having two pull-down control circuit alternation affect alternatively. The boost circuit is responsible for second rising of electric potential of the Q point to ensure the normal output of G(N) of the pull-up circuit.
Different GOA circuit may use different processes. LTPS (Low Temperature Poly-silicon) process has the advantage of high electron mobility and maturity of the technology, now widely used small and medium size displays. CMOS (Complementary Metal Oxide Semiconductor, a complementary metal oxide semiconductor) LTPS process with low power consumption, electronic mobility, noise margin width, etc., so gradually the use of panel makers, and so need to develop the GOA circuit corresponding to the CMOS LTPS process.